Tractography delineates microstructural changes in the trigeminal nerve after focal radiosurgery for trigeminal neuralgia

Purpose

Focal radiosurgery is a common treatment modality for trigeminal neuralgia (TN), a neuropathic facial pain condition. Assessment of treatment effectiveness is primarily clinical, given the paucity of investigational tools to assess trigeminal nerve changes. Since diffusion tensor imaging (DTI) provides information on white matter microstructure, we explored the feasibility of trigeminal nerve tractography and assessment of DTI parameters to study microstructural changes after treatment. We hypothesized that trigeminal tractography provides more information than 2D-MR imaging, allowing detection of unique, focal changes in the target area after radiosurgery. Changes in specific diffusivities may provide insight into the mechanism of action of radiosurgery on the trigeminal nerve.

Methods and Materials

Five TN patients (4 females, 1 male, average age 67 years) treated with Gamma Knife radiosurgery, 80 Gy/100% isodose line underwent 3Tesla MR trigeminal nerve tractography before and sequentially up to fourteen months after treatment. Fractional anisotropy (FA), radial (RD) and axial (AD) diffusivities were calculated for the radiosurgical target area defined as the region-of-interest. Areas outside target and the contralateral nerve served as controls.

Results

Trigeminal tractography accurately detected the radiosurgical target. Radiosurgery resulted in 47% drop in FA values at the target with no significant change in FA outside the target, demonstrating highly focal changes after treatment. RD but not AD changed markedly, suggesting that radiosurgery primarily affects myelin. Tractography was more sensitive than conventional gadolinium-enhanced post-treatment MR, since FA changes were detected regardless of trigeminal nerve enhancement. In subjects with long term follow-up, recovery of FA/RD correlated with pain recurrence.

Conclusions

DTI parameters accurately detect the effects of focal radiosurgery on the trigeminal nerve, serving as an in vivo imaging tool to study TN. This study is a proof of principle for further assessment of DTI parameters to understand the pathophysiology of TN and treatment effects.     

三叉神经痛的临床治疗进展

三叉神经痛是一种常见的面部疼痛性疾病,目前对其病因的认识并不明确。普遍认为压迫可导致三叉神经痛,致病原因包括血管因素和非血管因素,其次创伤也可导致三叉神经痛,常见于口腔外科手术后。三叉神经痛的治疗方法较多,首选药物治疗,包括全身用药和局部用药,药物治疗初期效果明显,但很难治愈三叉神经痛,而且需要长期服药,副作用较大,当药物治疗无效或者患者难以耐受其副作用时,可采用外科疗法进行辅助治疗。三叉神经痛的外科疗法主要包括无创的微血管减压术及有创的射频热凝术、球囊压迫术和甘油毁损术。近年来采用放射外科对三叉神经痛进行治疗,取得了确切效果。此外,还有一些关于其他治疗方法的文献报道,均有一定效果。本文对三叉神经痛病因的认识及临床治疗进展作一回顾性综述。     

Microvascular decompression: salient surgical principles and technical nuances

Trigeminal neuralgia is a disorder associated with severe episodes of lancinating pain in the distribution of the trigeminal nerve. Previous reports indicate that 80-90% of cases are related to compression of the trigeminal nerve by an adjacent vessel. The majority of patients with trigeminal neuralgia eventually require surgical management in order to achieve remission of symptoms. Surgical options for management include ablative procedures (e.g., radiosurgery, percutaneous radiofrequency lesioning, balloon compression, glycerol rhizolysis, etc.) and microvascular decompression. Ablative procedures fail to address the root cause of the disorder and are less effective at preventing recurrence of symptoms over the long term than microvascular decompression. However, microvascular decompression is inherently more invasive than ablative procedures and is associated with increased surgical risks. Previous studies have demonstrated a correlation between surgeon experience and patient outcome in microvascular decompression. In this series of 59 patients operated on by two neurosurgeons (JSN and PEK) since 2006, 93% of patients demonstrated substantial improvement in their trigeminal neuralgia following the procedure--with follow-up ranging from 6 weeks to 2 years. Moreover, 41 of 66 patients (approximately 64%) have been entirely pain-free following the operation. In this publication, video format is utilized to review the microsurgical pathology of this disorder. Steps of the operative procedure are reviewed and salient principles and technical nuances useful in minimizing complications and maximizing efficacy are discussed.     

原发性三叉神经痛和疱疹后三叉神经痛临床特征及射频热凝术后效果分析

摘要 目的：探讨原发性三叉神经痛（PTN）和疱疹后三叉神经痛（PHN）的临床特征,并比较经卵圆孔射频热凝术（RF-TC）治疗PTN和PHN的临床疗效。方法：随机选取2019年1月至2020年8月在我院治疗的三叉神经痛患者123例,其中原发性三叉神经痛90例,带状疱疹后神经痛33例。所有患者均通过RF-TC进行治疗,治疗后通过视觉模拟量表（VAS）、巴罗神经研究所疼痛强度量表对面部疼痛评分进行疼痛评估,通过巴罗神经研究所麻木评分进行麻木评定,通过健康问卷-9对患者抑郁情况进行评估,通过匹斯堡睡眠质量指数测量患者心理状态。结果：PTN患者发病年龄显著低于PHN患者（P<0.05）,而病程显著高于PHN患者（P<0.05）;PHN患者的眼支发生率高于PTN患者（39.39% vs 8.89%, P<0.05）。两组患者经RF-TC治疗前后VAS评分无显著差异（P>0.05）。PHN组从轻度到重度影响睡眠质量的比例显著高于PTN组（30.30% vs 10.00%, P<0.05）。PTN组患者治疗后中重度抑郁患者比例显著高于PHN组患者（21.11% vs 9.09%, P<0.05）。两组患者经RF-TC治疗后,临床治疗有效率、面麻木程度以及巴罗神经研究所疼痛强度量表评定的面部疼痛无显著差异（P>0.05）。结论：经卵圆孔射频热凝术治疗原发性三叉神经痛和带状疱疹后三叉神经痛是安全有效的,但治疗后疱疹后三叉神经痛失眠的发生率较高,而原发性三叉神经痛的抑郁发生率较高。     

A few remarks regarding 421 cases of trigeminal neuralgia]

Referring to the treatment of 421 patients with trigeminal neuralgia, the authors indicate an early alcoholization or exheyresis in case of therapeutical failure of systemic conservative treatment. Such a management prevents transformation of the peripheral into central neuralgia. Emphasis is on more frequent treatment of neuralgia by dental surgeons.     

Percutaneous Radio-Frequency Rhizotomy in the Treatment of Trigeminal Neuralgia

A percutaneous technique of selective partial trigeminal root coagulation was evaluated in the treatment of 38 patients suffering from trigeminal neuralgia, 1 patient with pain secondary to oral carcinoma and 1 patient with atypical facial pain. The pain of trigeminal neuralgia was relieved in 94.7 percent of patients. Pain was relieved in the patient with oral carcinoma, but not in the patient with atypical facial pain. There was no mortality and no permanent morbidity outside of the trigeminal nerve lesion. The procedure requires only a brief hospital stay without the time, expense and hazards of open cranial surgical procedures.     

家族性三叉神经痛

三叉神经痛是一种临床常见疾病,典型的三叉神经痛主要表现为阵发性、闪电样的疼痛发作,疼痛剧烈,常无法忍受,呈电灼、针刺、撕裂样,每次发作持续时间数秒至数分钟不等。疼痛多发生于单侧,常有扳机点表现,其多表现为散发,而家族性三叉神经痛报道罕见,至今世界范围内报道仅50余个家系,其临床表现及发病特点与散发性三叉神经痛存在明显差别,尽管散发三叉神经痛患者的病因为责任血管压迫三叉神经REZ区已被普遍接受,但关于家族性三叉神经痛的病因是否为血管压迫存在争议,其遗传模式也没有达成一致的意见,文章复习了相关文献,并通过对这些文献进行分析综合,结合我们治疗三叉神经痛的经验,对其病因、发病机制、诊断和治疗原则、遗传模式等作了系统综述。     

Electrical stimulation of the trigeminal tract in chronic, intractable facial neuralgia

In this paper the treatment of patients with chronic, intractable trigeminal neuralgia by invasive electrical stimulation of the Gasserion ganglion is reviewed. Two different surgical techniques are employed in this treatment. Most frequently, a method similar to the traditional technique for percutaneous glycerol and radiofrequency trigeminal rhizolysis is used: a small percutaneous stimulation electrode is advanced under fluoroscopic control through a thin needle via the foramen ovale to the Gasserian cistern. Some neurosurgeons use an open surgical technique by which the Gasserian ganglion is approached subtemporally and extradurally, and the bipolar pad electrode is sutured to the dura. When percutaneous test stimulation is successful (at least 50% pain relief) the electrode is internalized and connected to a subcutaneous pulse generator or RF-receiver. Data from 8 clinical studies, including 267 patients have been reviewed. Of all 233 patients with medication-resistant atypical trigeminal neuralgia 48% had at least 50% long term pain relief. The result of test stimulation is a good predictor of the long term effect, because 83% of all patients with successful test stimulation had at least 50% long term relief, and 70% had at least 75% long term relief. Patients generally preferred this invasive method over TENS. The success rate in patients with postherpetic trigeminal neuralgia was very low (less than 10%). It is suggested that the likelihood of pain relief by electrical stimulation is inversely related to the degree of sensory loss. It is concluded that invasive stimulation of the Gasserian ganglion is a promising treatment modality for patients with chronic, intractable, atypical trigeminal neuralgia.     

微球囊压迫介入治疗三叉神经痛

目的：三叉神经痛是口腔科常见疾病之一,病因不清。令患者难于忍受。多年来人们探索出很多的治疗手段,这些方法均不同程度伴有疗效、副损伤及并发症上的各种缺点。经研究经介入方法利用微球囊能改变了三叉神经半月节的解剖位置从而缓解其周围压力,进而治疗了三叉神经痛且疗效很好。结论：微球囊加压介入治疗三叉神经痛是目前有效治疗三叉神经痛的方法。     

CT引导下立体定向射频热凝三叉神经半月节对原发性三叉神经痛的疗效分析

目的：分析CT引导下立体定向射频热凝三叉神经半月节对原发性三叉神经痛的疗效,探讨其临床适用性。方法：选择从2011年5月至2012年12月于我院住院治疗原发性三叉神经痛的58例患者,在三维CT引导下采用通过BrainLAB手术计划系统经前入路卵圆孔穿刺三叉神经半月神经节,术中根据疼痛分布范围射频热凝三叉神经半月节。观察并比较治疗前后的VAS评分,临床疗效,术中和术后不良反应情况。结果：58例患者的穿刺手术均成功,术后1d、3d、6d的VAS评分均较治疗前显著降低（P〈0．01）;1周后58例患者中,有53例患者疼痛完全消失,l例患者偶然出现疼痛,但无需服用药物处理,共显效54例;4例患者疼痛有所减轻或疼痛发作频率降低,但仍需服用药物,或服用药物剂量较治疗前明显减少;疼痛无改善或者非用药不能缓解的持续痛仅1例。总有效例数为57例,总有效率达98．26％。术中发生不良反应6例,在术后均有所缓解。术后发生各种并发症共15例,均未明显影响手术效果。结论：CT引导可以较为准确的进入穿刺部位,使立体定向射频热凝三叉神经半月节手术更加顺利,达到治疗原发性三叉神经痛的理想效果,适合临床长期推广应用。     

Effectiveness of radiofrequency thermocoagulation in recurrent trigeminal neuralgia after previous retrogasserian rhizotomy

Between 1974 and 1984, 428 trigeminal neuralgia cases were treated by controlled radiofrequency thermocoagulation (RFTC). 29 had recurrent trigeminal neuralgia after intracranial surgery. 26 of the 29 patients were treated by retrogasserian rhizotomy and 3 by posterior fossa exploration. Among the 26 recurrent trigeminal neuralgia following retrogasserian rhizotomy, RFTC was effective in 23 cases (88.5%), and in 3 cases (11.5%) RFTC was effective for a short period. Repeated RFTC was unable to control the pain attacks which were later relieved by posterior fossa exploration and root section. Of the 3 recurrent trigeminal neuralgia following posterior fossa exploration, RFTC was effective in 2 cases (66.6%).     

Five-and-a-half years' experience with percutaneous retrogasserian glycerol rhizotomy in treatment of trigeminal neuralgia

The results of treating trigeminal neuralgia with percutaneous retroganglionic glycerol rhizotomy in 319 patients from an overall series of 394 patients with 459 operations carried out over a period of 5 1/2 years are reported. Idiopathic trigeminal neuralgia was the diagnosis in 252 patients. 34 patients had trigeminal neuralgia associated with multiple sclerosis. The remaining 33 patients suffered from symptomatic trigeminal neuralgia or atypical facial pain. 230 patients (91.3%) with idiopathic trigeminal neuralgia and 30 patients (88.2%) with multiple sclerosis reported complete freedom from pain. In 12 patients (4.8%) of those with tic douloureux and in 1 patient (2.9%) with multiple sclerosis, pain was alleviated, and the patients required a reduced pharmacotherapy. 10 patients (3.9%) and 3 patients (8.8%) were considered to be treatment failures. The rate of recurrences within the first 2 years was 10.9 and 40.0%, respectively. In the long-term, the rate of recurrences in patients with tic douloureux was 36.9%. 144 patients (45.1%) noticed a hypesthesia. 132 patients (41.4%) had hypalgesia following the procedure, and there was a decrease of symptoms in the long-term observation in 20.0% of the patients. 59 patients (18.5%) developed dysesthesia postoperatively which regressed only to an inappreciable extent in the long-term course. In 16 patients (5.0%) exclusively with a preexisting organic lesion or who had received surgical pretreatment, there was a loss of corneal sensation. The investigation showed on the one hand the effectiveness of the method, but on the other hand also the possibility of marked sensory disorder in selected cases.     

Microcirculatory changes in experimental trigeminal neuralgia in rats

Biomicroscopic studies of mesentery in trigeminal neuralgia rats caused by creation of a generator of pathologically enhanced excitation in trigeminal nerve caudal nucleus (injection 0.25-1.0 DLM Tetanus toxin) have shown the microcirculatory disorders, venular permeability, mast cells degranulation, and an increase in lymphatic contractile activity. Microcirculatory disorders intensity and adaptation reaction appearance correlated with trigeminal neuralgia clinical picture.     

A method for bulbospinal trigeminal nucleotomy in the treatment of facial deafferentation pain

Many types of facial pain are difficult to treat, such as postherpetic, posttraumatic, or pain following denervation procedures used in the treatment of trigeminal neuralgia (anesthesia dolorosa), all of which involve deafferentation of the spinal trigeminal nucleus.     

Microsurgical Vascular Decompression for Trigeminal Neuralgia and Hemifacial Spasm

Vascular cross-compression of cranial nerves has been proposed as the cause of cranial neuropathies, including trigeminal neuralgia and hemifacial spasm. Over the last decade we have used microsurgical vascular decompression to treat these two disorders. Results in 50 patients treated for trigeminal neuralgia have been excellent in 42, good in 5 and poor in 2; and 1 patient was cured after a second operation. Results in 22 patients treated for hemifacial spasm have been excellent in 18, good in 2 and fair in 1. One patient died. There were no late recurrences of symptoms.The pathophysiological mechanisms of trigeminal neuralgia and hemifacial spasm remain unknown.     

Epileptiform activity in the somatosensory cortex of rats with trigeminal neuralgia]

It was shown in experiments on rats that penicillin 1 microliter microinjection (100 U) into the caudal nucleus of the spinal tract of the trigeminal nerve, accounting for formation of a generator of pathologically enhanced excitation (GREE), brings about in rats the pain syndrome with characteristic for trigeminal neuralgia behavioural manifestations and the emergence of epileptiform activity in the somatosensory cortex, especially pronounced in the contralateral hemisphere. The emergence of this activity reflects, on the one hand, the action of the GREE in the caudal nucleus of the trigeminal nerve and, on the other hand, the involvement of the somatosensory cortex taking over stimulation from the hyperactive caudal nucleus, into formation of a pathological algic system of this form of trigeminal neuralgia.     

改良微血管减压术治疗复发性三叉神经痛的疗效及安全性分析

目的:探讨改良微血管减压术(MVD)治疗复发性三叉神经痛的疗效及安全性。方法:回顾性分析2010年至2015年收治的50例复发性三叉神经痛患者,2012年前采取常规MVD手术方法(MVD组,n=22),2012年后采取改良MVD的手术方法(改良MVD组,n=28)。MVD组采用传统MVD对三叉神经根进行全程减压,即沿首次切口入路,依次切开皮下、肌筋膜,充分分离骨窗边缘的瘢痕组织,适当扩大骨窗直至硬脑膜充分暴露。切开硬膜,锐性分离蛛网膜后探查Meckel腔至神经出脑区(REZ),仔细探查三叉神经全段,分离压迫神经的责任血管以及首次手术置入的Teflon垫棉,对三叉神经进行全程减压。改良MVD组在此基础上,探查三叉神经颅内段及其周围结构,解剖三叉神经脑干延伸段,垫开小脑上动脉对三叉神经脑干延伸段的压迫。比较两组术后缓解率、并发症、复发情况。结果:改良MVD组术后缓解率为100.0%,显著高于MVD组72.7%(P0.05);两组术后并发症的发生率比较差异无统计学意义(P0.05);改良MVD组术后1年复发率为0%,显著低于MVD组22.7%(P0.05)。结论:MVD术中三叉神经根全程减压联合脑干延伸段减压治疗复发性三叉神经痛患者可有效缓解疼痛,降低术后复发风险,且不增加术后并发症。     

Trigeminal Neuralgia and Dental Malocclusions

Out of 39 patients with intractable trigeminal neuralgia seven have had continuing relief for over three years after dental treatment. Five out of six recent consecutive edentulous patients had immediate improvement. More radical treatment, such as ganglion injection or nerve root section, has been at least postponed.     

Favorable outcome of decompression of the trigeminal nerve in a case of bilateral neuralgia

A case of the bilateral trigeminal neuralgia produced by compression of the V cranial nerve roots by the branch of the anterior lower cerebral artery and post-hemorrhagic aggregates is presented. Complete recovery was obtained in the result of 2-stage, intracranial relief of the right and left trigeminal nerve roots. Neurologists share the opinion that intracranial surgical relief of the V cranial nerve root produces favourable result in case of trigeminal neuralgia resistant to pharmacotherapy.